It is known in the prior art to cast metals by heating in a crucible above a mold, and then discharging the molten metal through a hole into the mold, either by gravity alone, or by that supplemented with gas pressure or vacuum from the mold side, Kidowaki et al. U.S. Pat. No. 4,254,817, "Metal Casting Apparatus", granted Mar. 10, 1981; Waterstrat U.S. Pat. No. 4,538,671, "Arc Furnace for the Production of Small Investment Castings of Reactive or Refractory Metals such as Titanium", granted Sep. 3, 1985.
Investments with binding through a magnesium oxide ammonium phosphate reaction are known, as are such investments with fillers a mixture of zirconia and alumina.